Magnetic tape provides a good mass storage device for storing large quantities of computer data. In the prior art, the most common type of magnetic tape storage unit uses reels of magnetic tape. Newer types of magnetic tape storage units utilize magnetic tape cartridges. One type of tape cartridge in particular is referred to in the industry as a 3480 cartridge. The 3480 tape cartridge is becoming more and more popular because it has a higher storage density than other tape devices and it lends itself to robotic handling. The 3480 tape cartridge contains a single spool of tape. The free end of the tape is coupled to a load block. When the cartridge is used, the load block is transferred to a take-up spool external to the cartridge. The cartridge contains a locking mechanism that must be disengaged before the tape can be wound or unwound from the cartridge.
Magnetic tape, particularly high density magnetic tape, must be periodically cleaned to satisfactorily maintain its data storage capability. Debris and high spots on the tape prevent good tape-to-head contact, resulting in a loss of some data.
As with any other magnetic tape, the tape in a 3480 cartridge must be periodically cleaned. Automatic cleaning the tape in a 3480 cartridge is made difficult by the structure of the cartridge. For example, the locking mechanism must be disengaged to allow the tape to be unwound for cleaning. Furthermore, the load block must be manipulated to remove the tape from the cartridge. Further still, the length of tape in a 3480 cartridge can vary from between 450 to 600 feet. The tape has no markers to indicate its beginning or end and the end of the tape is not physically coupled to the cartridge. Thus, when the tape is unwound from the cartridge for cleaning, some tape must be left on the cartridge spool, otherwise the end of the tape will be removed from the cartridge.
It is an object of the present invention to provide an apparatus for automatically cleaning tape in magnetic tape cartridges in general, and in particular, for automatically cleaning magnetic tape cartridges of the 3480 type.
It is another object of the present invention to provide an apparatus that can detect the approach of the end of the tape so as not to remove all of the tape from the cartridge.
It is a further object of the present invention to provide an apparatus for automatically cleaning tape in cartridges wherein the tape is rewound into the cartridge under a constant tension.